Over the past twenty years a multitude of proposals have been put forth for drilling lateral channels into hydrocarbon bearing formations encountered in a well which has a vertical steel casing installed in it. Schellstede U.S. Pat. No. 4,640,362, Schellstede U.S. Pat. No. 5,183,111, Dickinson U.S. Pat. No. 4,527,639, Landers U.S. Pat. No. 5,413,184, Peters U.S. Pat. No. 5,392,858, rely on the casing being firstly perforated with a tool of some type, ranging from a punch in Schellstede U.S. Pat. No. 4,640,362 to a drill bit in Landers U.S. Pat. No. 5,413,184. After the hole is made in the casing, a water jet head and its connection hose, which is used to make a lateral channel in the formation, is moved out into the formation while water mixed with appropriate chemicals is pumped through the hose and jet head. The water is pumped down the well to the hose through small diameter tubing. The action of the jet on the formation erodes the formation and produces a lateral channel from the steel casing to the extent that the hose and jet head will reach. The jet head configurations have a jet or jets facing forward to erode material and jets facing rearward to help move the jet head and its connecting hose or pipe into the formation. The rearward facing jets also flush the eroded material back inside the well casing. Jets have been used in industry for many years for cleaning boiler tubes and other blocked and corrosion reduced diameters of tubes in refinery process equipment. There is a multitude of such jet head configurations on the market and their use for drilling wells, including lateral wells, is not new.
There are also available jet perforating systems which are positioned in a casing where it is required to bore through to the formation and such jets are supplied with fluid and an abrasive under high pressure and volume, which erodes a hole in the casing. These systems have been in use for over twenty-five years and are well known in the industry but are not the method of choice for the large majority of perforating services.
All of the various lateral jet drilling devices require that a hole be made in the casing for the jet head and hose to go through to get into the formation where the jet will drill the lateral channel. The main difference in the systems is how the hole is made in the casing. For each lateral channel, the jet head and hose must either be removed from the tool head and the drill system moved in and actuated or some mechanism must move the tool up or down in the casing to get the drilling device in place. There is also no provision for installing a casing in the lateral channel that will keep the channel from collapsing after the drilling is complete.
In order to drill several holes at different angles around the casing, a large number of runs of this type of equipment will be required. The various systems designed require that there be large tubing run in the well in order to house and support the various devices. This type of system requires a service rig on site to initially lower the equipment in the well. Reliance on tubing rotation (Landers U.S. Pat. No. 5,413,184) in order to orient the lateral holes being drilled in the formation is prone to error due to the tubing not rotating the same number of degrees at the bottom as it has been turned at the top. It is known that in wells that have not been drilled straight that the friction of the tubing on the casing can restrain the tool at the bottom from turning at all while the tubing at the top rotates a full turn. The accurate depth positioning of these tools in the well is also questionable. Typically, the position of the tool in the well is calculated by measuring the length of tubing that is run in the well and comparing this against electric well logging, wherein the well logging cable footage is recorded to the exact depth. The depth is also confirmed by counting casing collars.